1. Field of the Invention
The invention relates to electric-motor drive devices and more particularly to improve electric motor drives for auxiliary devices in motor vehicles, such as sliding roofs, window controls, windshield wipers, and the like,.
2. Description of the Prior Art
In a known drive device of this type disclosed in German Utility Model DE 92 06 269 U1, the cup-shaped or cap-shaped motor housing is slipped onto a cylindrical post of the gear to housing; the edge of its cap is covered by an annular flange embodied on the post. Between the edge of the cap and the annular flange, there is a sealing ring.
In another known drive device disclosed in German Patent Disclosure DE 25 56 240 A1, the fixation of the gear housing and motor housing to one another is done by providing each housing with a radial shoulder, which after the two housings have been joined together is located spaced apart from and in front of the shoulder of the other housing, and a fastening element that has clamping faces cooperating in wedgelike fashion with the shoulders clamps the two housings together.
The drive device of the invention has the advantage over the prior art that production is simplified and thus made less expensive by eliminating the shoulders, which have to be formed separately on the housings, and the loose fastening element. Also eliminated are elements protruding past the outside diameter of the housings, so that the requisite installation space for the drive device is reduced. Roller-burnishing according to the invention assures an improved introduction of force from the motor housing to the gear housing and a rigid connection between the housings, with a favorable effect on noise produced by the drive device. At the same time, by the large-area, intimate bond between the housings that is attained, an improved heat transfer from the motor housing to the gear housing and thus improved heat dissipation from the motor are attained. Furthermore, the roller-burnished connection brings about good sealing at the transition between the two housings. Roller-burnishing has been set forth in U.S. Pat. No. 6,056,263 column 2, line 61 through column 3, line 44, which is incorporated herein by reference.
In a preferred embodiment of the invention, the roller-burnishing is performed at two points, longitudinally spaced apart from one another, in the slip-on region of the motor housing onto the gear housing. This creates a very reliable connection, in which for long periods, even under extreme operating conditions, no play can occur between the two housings.
In an advantageous embodiment of the invention, the gear housing, in the slip-on region of the motor housing, has an annular groove into which an encompassing annular bead, stamped out of the motor housing by roller-burnishing, protrudes with positive engagement. The provision of the annular groove makes it easier to press the motor housing material into the gear housing, and only much-reduced roller-burnishing forces are required. A good positive engagement connection is created between the annular groove and the annular bead.
Greater strength of this connection is attained whenever, in accordance with an advantageous embodiment of the invention, on the gear housing in the motor housing slip-on region, an encompassing radial shoulder remote from the motor housing is additionally embodied, and the radial shoulder is engaged from behind by an annular collar bent inward from the motor housing by roller-burnishing. The motor housing is then fixed on the gear housing at two spaced-apart points.